How do I make my Character Jump?

Hello, so I am following this tutorial on youtube on creating an endless runner for my 3D unity game. The video is very informal however the maker did not include a way for the character to jump. So I am asking is, is there a way to add a jump feature to the script I already have so far?

 using UnityEngine;
 using System.Collections;
 
 public class PlayerMotor : MonoBehaviour 
 {
     private CharacterController controller;
     private Vector3 moveVector;
 
     private float speed = 5.0f;
     private float verticalVelocity = 0.0f; 
     private float gravity = 12.0f;
 
     private float animationDuration = 3.0f;
 
     // Use this for initialization
     void Start () {
         controller = GetComponent<CharacterController> ();
     }
     
     // Update is called once per frame
     void Update () {
 
         if (Time.time < animationDuration) 
         {
             controller.Move (Vector3.forward * speed * Time.deltaTime);
             return;
         }
 
         moveVector = Vector3.zero;
 
         if (controller.isGrounded)
         {
             verticalVelocity = -0.5f;
         }
         else 
         {
             verticalVelocity -= gravity * Time.deltaTime;
         }
 
         // X - Left and Right
         moveVector.x = Input.GetAxisRaw ("Horizontal") * speed;
 
         // Y - Up and Down
         moveVector.y = verticalVelocity;
 
         // Z - Forward and Backward
         moveVector.z = speed;
 
         controller.Move (moveVector * Time.deltaTime);
     }
 }